5-phenyl-3H,6H-1,3,4-oxadiazine-2-ones in treatment of heart failure and hypertension

ABSTRACT

Heterocyclic compounds of the formula ##STR1## wherein either X is --CR 1  R 2  and Y is --O--, --S-- or --NR 3  --, wherein R 1 , R 2  and R 3 , which may be the same or different, each is hydrogen or alkyl of up to 4 carbon atoms; 
     or X is --O--, --S-- or --NH-- and Y is --CR 1  R 2  -- wherein R 1  and R 2  have the meanings stated above; 
     wherein either R 4  is hydrogen, fluoro or chloro, or alkyl, alkenyl, halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl or alkoxy each of up to 6 carbon atom, and R 5 , R 6  and R 7 , which may be the same or different, each is hydrogen, fluoro, chloro, bromo or iodo, or alkyl, alkenyl, halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl or alkoxy each of up to 6 carbon atoms, provided that R 4 , R 5 , R 6  and R 7  are not all hydrogen; 
     or R 4  is bromo and R 5 , R 6  and R 7  have the meanings stated above, provided that R 5 , R 6  and R 7  are not all hydrogen; 
     or R 4  and R 5  together, or R 5  and R 6  together, or R 4  and R 7  together, form the --CH═CH--CH═CH-- group and the other two of R 4 , R 5 , R 6  and R 7  have the meanings stated above; processes for their manufacture and pharmaceutical compositions containing them. The compounds possess cardiotonic and/or antihypertensive activity.

This is a division of application Ser. No. 660,135 filed Oct. 12, 1984,now U.S. Pat. No. 4,584,298; which is a division of application Ser. No.436,801, filed Oct. 26, 1982, now U.S. Pat. No. 4,495,185.

This invention relates to new heterocyclic compounds, some of whichpossess cardiotonic properties, some of which possess antihypertensiveproperties and some of which possess both said properties.

Many 6-aryl-dihydropyridazin-3-one derivatives are known which possesspharmaceutical properties affecting the cardiovascular system. These aredescribed for example, in the Journal of Medicinal Chemistry, 1974, 17,273-286 and in the Journal of Heterocyclic Chemistry, 1974, 11, 755-761,and there is much related patent literature.

When an additional hetero-atom is inserted into the pyridazine nucleus,most of the simple structures have been described in the academicchemical literature. Thus, for example:

2-phenyl-4H,6H-1,3,4-thiadiazin-5-one and its 6-methyl analogue areknown from Chemical Abstracts, 1948, 42, 5919 and 1956, 50, 7817;

5-phenyl-3H,6H-1,3,4-thiadiazin-2-one and its 6-methyl analogue areknown from Leibig's Annalen der Chemie, 1977, 791 and from this articleare also known the corresponding p-bromophenyl and 4-biphenylylanalogues;

2-phenyl-4H,6H-1,3,4-oxadiazin-5-one is known from Receuil des Travauxchimiques des Pays Bas, 1929, 48, 417 and o-hydroxyphenyl analoguesthereof are known from J. Heterocyclic Chemistry, 1970, 7; 927;

3-phenyl-4,5-dihydro-5-methyl-1H-1,2,4-triazin-6-one is known from J.Heterocyclic Chemistry, 1978, 15, 1271;

6-phenyl-4,5-dihydro-2H-1,2,4-triazin-3-one and its 4-methyl analogueare known from Chemical Abstracts, 1970, 73, 35334.

From the patent literature 5-phenyl-3H,6H-1,3,4-oxadiazin-2-one and thecorresponding 4-bromophenyl and 2-naphthyl analogues are known asblowing agents in the plastics industry, from U.S. Pat. Nos. 4,097,425,4,105,848 and 4,158,094.

None of the abovementioned references discloses any pharmacologicalutility for any of the compounds described. The only references topharmacological activity in this kind of compound of which applicantsare aware appear in U.S. Pat. No. 3,514,455, which describes various4,6-disubstituted-2-phenyl-4H,6H-1,3,4-thiadiazin-5-one derivativeswhich are claimed to possess antipyretic, analgesic, anti-inflammatoryand antiedema activities, and in U.S. Pat. No. 3,946,010, whichdescribes various 3-o-aminophenyl-4,5-dihydro-1H-1,2,4-triazine-6-onederivatives which are claimed to possess anti-inflammatory activity.

A compound of considerable interest at present as a cardiotonic agent isa pyridone derivative known by the name AMRINONE, which has thestructure: ##STR2##

We have now found that various phenyl-thiadiazinone, oxadiazinone ortriazinone derivatives which bear a substituent in one or more of the2-, 3-, 4- and 5-positions of the phenyl nucleus possess valuablecardiotonic and/or antihypertensive properties.

According to the invention there is provided a heterocyclic compound ofthe formula: ##STR3## wherein either X is --CR¹ R² -- and Y is --O',--S-- or --NR³ --, wherein R¹, R² and R³, which may be the same ordifferent, each is hydrogen or alkyl of up to 4 carbon atom;

or X is --O--, --S-- or --NH-- and Y is --CR¹ R² --wherein R¹ and R²have the meanings stated above;

wherein either R⁴ is hydrogen, fluoro or chloro, or alkyl, alkenyl,halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl or alkoxy each ofup to 6 carbon atoms, and R⁵, R⁶ and R⁷, which may be the same ordifferent, each is hydrogen, fluoro, chloro, bromo or iodo, or alkyl,alkenyl, halogenoalkyl, aminoalkyl, acylaminoalkyl, hydroxyalkyl,alkoxyalkyl or alkoxy each of up to 6 carbon atoms, provided that R⁴,R⁵, R⁶ and R⁷ are not all hydrogen;

or R⁴ is bromo and R⁵, R⁶ and R⁷ have the meanings stated above,provided that R⁵, and R⁶ and R⁷ are not all hydrogen;

or R⁴ and R⁵ together, or R⁵ and R⁶ together, or R⁴ and R⁷ together,form the --CH═CH--CH═CH-- group (such that together with the benzenering they form a naphthalene ring), and the other two of R⁴, R⁵, R⁶ andR⁷ have the meanings stated above.

A suitable value for R¹, R² or R³ when it is alkyl is, for example,methyl or ethyl.

A suitable value for R⁴, R⁵, R⁶ or R⁷ when it is alkyl, alkenyl,halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl or alkoxy is, forexample, methyl, ethyl, allyl, chloromethyl, trifluoromethyl,aminomethyl, hydroxymethyl, 2-hydroxyethyl, methoxymethyl, methoxy orethoxy.

A preferred heterocyclic compound of the invention has the formulastated above wherein either:

X is --CH₂ -- and Y is --O--, --S--, --NH-- or --N(CH₃)--;

or X is --CH(CH₃)-- and Y is --S--;

or X is --O--, --S-- or --NH-- and Y is --CH₂ --;

wherein either R⁴ is hydrogen, fluoro, chloro or trifluoromethyl, oralkyl or alkoxy each of up to 4 carbon atoms, and R⁵, R⁶ and R⁷, whichmay be the same or different, each is hydrogen, fluoro, chloro, bromo,iodo or trifluoromethyl, or alkyl or alkoxy each of up to 4 carbonatoms, provided that R⁴, R⁵, R⁶ and R⁷ are not all hydrogen;

or R⁴ is bromo and R⁵, R⁶ and R⁷ have the last mentioned meanings statedabove, provided R⁵, R⁶ and R⁷ are not all hydrogen;

or R⁴ and R⁵ together, or R⁵ and R⁶ together, form --CH═CH--CH═CH-- andthe other two of R⁴, R⁵, R⁶ and R⁷ are hydrogen.

A particularly preferred heterocyclic compound of the invention has theformula stated above wherein either:

X is --CH₂ -- and Y is --O--, --S-- or --NH--;

or X is --C(CH₃)-- and Y is --S--;

or X is --O--, --S-- or --NH-- and Y is --CH₂ --;

wherein R⁴ is hydrogen, fluoro, chloro or trifluoromethyl, or alkyl oralkoxy each of up to 4 carbon atoms, R⁷ is hydrogen and R⁵ and R⁶, whichmay be the same or different, each is hydrogen, fluoro, chloro, bromo ortrifluoromethyl, or alkyl or alkoxy each of up to 4 carbon atoms,provided that R⁴, R⁵ and R⁶ are not all hydrogen.

Specific heterocyclic compounds of the invention are hereinafterdescribed in the Examples. Of these, a preferred compound whichpossesses cardiotonic activity is 6-(m-chlorophenyl-, m-bromophenyl- orm-trifluoromethylphenyl)4,5,-dihydro-1,2,4-triazin-3(2H)-one, or,especially,5,6-dihydro-2-(2,4,5-trimethoxy-phenyl)-4H-1,3,4-thiadiazin-5-one.

A preferred compound which possesses antihypertensive activity is5,6-dihydro-2-(m-methoxyphenyl orp-chlorophenyl)-4-H-1,3,4-thiadiazin-5-one; or 5-(m-chlorophenyl-,3,4-dichlorophenyl-, 3,5-dichlorophenyl-or2-naphthyl-)-3H,6H-1,3,4-thiadiazin-2-one, and of these an especiallypreferred compound is5-(3,4-dichlorophenyl)-3H,6H-1,3,4-thiadiazin-2-one.

A preferred process for the manufacture of a compound of the inventionwherein X is oxygen or sulphur and Y is --CR¹ R² -- comprises thereaction of a hydrazide or thiohydrazide of the formula: ##STR4##wherein R⁴, R⁵, R⁶ and R⁷ have the meanings stated above and X issulphur or oxygen, with an acid of the formula:

    Hal--CR.sup.1 R.sup.2 --COOH

wherein R¹ and R² have the meanings stated above and wherein hal is ahalogen atom, for example the chlorine or bromine atom, or with areactive derivative thereof.

When X is sulphur the acid is preferably used as a reactive derivativethereof, for example a methyl or ethyl ester, and the reaction may becarried out in aqueous solution, in the presence of a base, for example,sodium hydroxide, at laboratory temperature.

When X is oxygen the acid is preferably used as a reactive derivativethereof, for example the acyl halide, and the reaction carried out intwo stages. The benzoylhydrazine may be reacted with the acyl halide inan inert solvent, for example toluene, in the presence of a base, forexample potassium carbonate. The diacyl hydrazine thus obtained may thenbe reacted with a base, for example sodium hydride, in a dipolar aproticsolvent, for example dimethylformamide, or with an alkali metalcarbonate in acetone, and the reaction may be carried out at an elevatedtemperature, for example at about 100° C.

A preferred process for the manufacture of a compound of the inventionwherein X is --CR¹ R² -- and Y is sulphur comprises the reaction of aphenacyl halide of the formula: ##STR5## wherein R¹, R², R⁴, R⁵, R⁶, R⁷and Hal have the meanings stated above, with a thiocarbazate of theformula:

    H.sub.2 N.NH.CS--O--R.sup.10 or H.sub.2 N.NH.CSO.sup.- M.sup.+

wherein R¹⁰ is alkyl of up to 4 carbon atoms, for example methyl orethyl, and wherein M⁺ is an alkali metal or ammonium ion.

The reaction may be carried out in an organic diluent or solvent, forexample acetonitrile or ethanol, at an elevated temperature, for exampleat the boiling point of the diluent or solvent.

A preferred process for the manufacture of a compound of the inventionwherein X is --CR¹ R² -- and Y is oxygen comprises the cyclisation of acompound of the formula: ##STR6## wherein R¹, R², R⁴, R⁵, R⁶, R⁷ and R¹⁰have the meanings stated above. The cyclisation may be carried out inthe presence of a base, for example sodium ethoxide, in a diluent orsolvent, for example ethanol, at laboratory temperature.

The starting material for the last-mentioned reaction may be obtained bythe reaction of a compound of the formula: ##STR7## wherein R¹, R², R⁴,R⁵, R⁶ and R⁷ have the meanings stated above, with an alkyl carbazate ofthe formula:

    H.sub.2 N--NH.COOR.sup.10

wherein R¹⁰ has the meaning stated above.

A preferred process for the manufacture of a compound of the inventionwherein X is --NH-- and Y is --CR¹ R² -- comprises the reaction of acompound of the formula: ##STR8## wherein R¹, R², R⁴, R⁵, R⁶, R⁷ and R¹⁰have the meanings stated above (the two R¹⁰ substituents being the sameor different alkyl radicals of up to 4 carbon atoms), with hydrazine.

The reaction may be carried out in a diluent or solvent, for exampleethanol, at a temperature up to the boiling point of the diluent orsolvent.

The starting material for the last-mentioned reaction may be obtainedeither by the reaction of a compound of the formula: ##STR9## whereinR¹, R², R⁴, R⁵, R⁶, R⁷ and R¹⁰ have the meanings stated above, with anoxonium trifluoroborate of the formula (R¹⁰)₃ OBF₄, wherein R¹⁰ has themeaning stated above, or by the reaction of a compound of the formula:##STR10## wherein R⁴, R⁵, R⁶, R⁷ and R¹⁰ have the meanings stated above,with a glycine ester of the formula H₂ NR¹ R² COOR¹⁰, wherein R¹, R² andR¹⁰ have the meanings stated above.

A preferred process for the manufacture of a compound of the inventionwherein X is --CR¹ R² -- and Y is --NR³ -- comprises the reaction of acompound of the formula: ##STR11## wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷and R¹⁰ have the meanings stated above, with hydrazine.

The reaction may be carried out in a diluent or solvent, for exampleethanol or isopropanol, at a temperature up to the boiling point of thediluent or solvent.

The starting material for the last-mentioned process may be obtained bythe reaction of a compound of the forumla: ##STR12## wherein R¹, R², R³,R⁴, R⁵, R⁶ and R⁷ have the meanings stated above, with a chloroformateof the formula R¹⁰ OCOCl, wherein R¹⁰ has the meaning stated above.

A compound of the invention wherein R³ is alkyl may be obtained by thealkylation of the corresponding compound wherein R³ is hydrogen.

As stated above, some of the heterocyclic compounds of the inventionpossess cardiotonic activity. This may be demonstrated by their abilityto increase the rate of change of aortic blood pressure in theanaesthetised cat. At a dose of the compound which produces an effectiveincrease in said rate of change, that is, greater than a 25% increase,no symptom of toxicity is apparent.

As stated above, some of the heterocyclic compounds of the inventionpossess antihypertensive activity, as demonstrated by their ability todecrease the blood pressure of a normotensive cat or of a spontaneouslyhypertensive rat. The antihypertensive activity may also be demonstratedby the vasodilation effect produced by the heterocyclic compounds of theinvention as shown by their ability to reduce spontaneous contraction ina rat portal vein preparation.

The heterocyclic compound of the invention may be administered towarm-blooded animals, including man, in the form of a pharmeceuticalcomposition comprising as active ingredient at least one heterocycliccompound of the invention in association with apharmaceutically-acceptable diluent or carrier therefor.

A suitable composition is, for example, a tablet, capsule, aqueous oroily solution or suspension, emulsion, injectable aqueous or oilysolution or suspension, dispersible powder, spray or aerosolformulation.

The pharmaceutical composition may contain, in addition to theheterocyclic compound of the invention, one or more drugs selected fromsedatives, for example phenobarbitone, meprobamate, chlorpromazine andbenzodiazepine sedative drugs, for example chlordiazepoxide anddiazepam; vasodilators, for example hydralazine, glyceryl trinitrate,pentaerythritol tetranitrate and isosorbide dinitrate; diuretics, forexample chlorothiazide, hydrochlorothiazide, amiloride, bendrofluazideor chlorothalidone; β-adrenergic blocking agents, for examplepropranolol or atenolol; cardiac membrane stabilising agents, forexample quinidine; agents used in the treatment of Parkinson's diseaseand other tremors, for example benzhexol; and cardiotonic agents, forexample digitalis preparations.

When used for the treatment of acute or chronic heart failure or ofhypertension in man, it is expected that the heterocyclic compound wouldbe given to man at a total oral dose of between 100 mg. and 2000 mg.daily, at doses spaced at 6-8 hourly intervals, or at an intravenousdose of between 5 mg. and 100 mg.

Preferred oral dosage forms are tablets or capsules containing between50 and 500 mg., and preferably 100 mg. or 500mg., of active ingredient.Preferably intravenous dosage forms are sterile aqueous solutions of theheterocyclic compound containing between 0.05% and 1% of activeingredient, and more particularly containing 0.1% w/v of activeingredient.

The invention is illustrated but not limited by the following Examples:

EXAMPLE 1

A mixture of 2-bromo-p-methoxyacetophenone (4.58 g.),methoxythiocarbonylhydrazine (3.07 g.) and acetonitrile (12.5 ml.) washeated under reflux for 5 hours and then cooled and filtered. Thefiltrate was evaporated to dryness under reduced pressure and theresidue was crystallised from ethanol. There was thus obtained5-p-methoxyphenyl-3H,6H-1,3,4-thiadiazin-2-one, m.p. 126°-128°.

The process described above was repeated using the appropriate2-bromo-alkanophenone as starting material (most of these are knowncompounds, any novel one being prepared by conventional means). Therewere thus obtained the compounds described in the following table:

    __________________________________________________________________________     ##STR13##                                                                                                     Crystallisation                              R.sup.1                                                                          R.sup.7                                                                           R.sup.4                                                                              R.sup.5                                                                             R.sup.6                                                                              m.p. (°C.)                                                                   Solvent                                      __________________________________________________________________________    H  H   H      F     H      144-146                                                                             ethanol                                      H  H   F      H     H      189-191                                                                             methanol                                     H  H   H      H     Cl     169-172                                                                             ethyl acetate/                                                                petroleum ether                                                               (b.p. 40-60° C.)                      H  H   H      Cl    H      142-144                                                                             toluene                                      H  H   Cl     H     H      185-187                                                                             ethanol                                      H  H   F      Cl    H      176-178                                                                             methanol                                     H  H   Cl     Cl    H      184-187                                                                             methanol                                     H  Cl  H      Cl    H      164-165                                                                             isopropanol                                  H  H   Br     Cl    H      182-185                                                                             methanol                                     H  H   CH.sub.3 O                                                                           Cl    H      160-161                                                                             isopropanol                                  H  H   CH.sub.3                                                                             Cl    H      150-152                                                                             cyclohexane/                                                                  ethyl acetate                                H  Cl  Br     Cl    H      178-179                                                                             cyclohexane                                  H  H   H      Br    H      136-137                                                                             methanol                                     H  H   H      I     H      151-153                                                                             ethyl acetate/                                                                petroleum ether                                                               (b.p. 40-60° C.)                      H  H   H      CF.sub.3                                                                            H      154-157                                                                             toluene                                      H  H   H      CH.sub.3 O                                                                          H      161-162                                                                             ethanol                                      H  H   CH.sub.3 O                                                                           CH.sub.3 O                                                                          H      157-159                                                                             methanol                                     H  CH.sub.3 O                                                                        CH.sub.3 O                                                                           H     CH.sub.3 O                                                                           116-121                                                                             aqueous                                                                       methanol                                     H  CH.sub.3 O                                                                        CH.sub.3 O                                                                           CH.sub.3 O                                                                          H      189-191                                                                             acetonitrile                                 H  H   iso-C.sub.4 H.sub.9                                                                  H     H      134-135                                                                             cyclohexane                                  H  H   CH.sub.3                                                                             CH.sub.3                                                                            H      133-135                                                                             ethanol                                      CH.sub.3                                                                         H   H      Cl    H      138-139                                                                             ethyl acetate/                                                                petroleum ether                                                               (b.p. 40-60° C.)                      CH.sub.3                                                                         H   Cl     Cl    H      168-170                                                                             methanol                                     H  H   H      CHCHCHCH     198-199                                                                             methanol                                     H  H    CHCHCHCH    H      175-177                                                                             acetone                                      CH.sub.3                                                                         H   CHCHCHCH     H      183-185                                                                             methanol                                     __________________________________________________________________________

EXAMPLE 2

Sodium hydride (1.0 g. of a 50% suspension in mineral oil) was added toa solution of N-m-chlorobenzoyl-N¹ -chloroacetylhydrazine (4.69 g.) indimethylformamide (100 ml.) and the mixture was heated at 120°-130° C.for 2 hours, cooled, diluted with saturated aqueous sodium chloridesolution (200 ml.) and acidified to pH 6 with aqueous 2N-hydrochloricacid. The mixture was extracted three times with ethyl acetate (80 ml.each time) and the extract was washed five times with water (50 ml. eachtime), dried and evaporated to dryness. The residue was crystallisedfrom ethanol and there was thus obtained2-m-chlorophenyl-4H,6H-1,3,4-oxadiazin-5-one, m.p. 173°-175° C.

The diacylhydrazine used as starting material was obtained as follows:

Triethylamine (2.8 ml.) was added to a stirred suspension ofm-chlorobenzohydrazide (3.4 g.) in dioxan (100 ml.), followed bychloroacetyl chloride (1.5 ml.) added dropwise, and the mixture wasstirred for 24 hours and then evaporated to dryness under reducedpressure.

There was thus obtained as residue N-m-chlorobenzoyl-N¹-chloroacetylhydrazine, which was used without further purification.

The process described above was repeated except that the appropriatebenzohydrazide was used as initial starting material in place ofm-chlorobenzohydrazide. There were thus obtained the compounds describedin the following table:

    ______________________________________                                         ##STR14##                                                                                                      Crystallisation                             R.sup.7                                                                              R.sup.4  R.sup.5   m.p. (°C.)                                                                     Solvent                                     ______________________________________                                        H      methoxy  H         161-163 methanol*                                   H      fluoro   H         190-192 methanol                                    chloro H        chloro    178-180 isopropanol.sup.+                           ______________________________________                                         *The intermediate .sub.--N-pmethoxybenzoyl-.sub.--N.sup.1                     -chloroacetylhydrazine had m.p. 185-188° C. after crystallisation      from ethyl acetate.                                                           .sup.+ The intermediate .sub.--N(3,5dichlorobenzoyl)-.sub.--N.sup.1           chloroacetylhydrazine had m.p. 222-223° C.                        

EXAMPLE 3

A mixture of ethyl p-trifluoromethylhippurate [13.0 g; m.p. 140°-142°C.; prepared from p-trifluoromethylbenzoic acid (12.8 g.), thionylchloride (75 ml.) and ethyl glycinate hydrochloride (16.35 g.)],triethyloxonium fluoroborate (11.2 g.) and methylene chloride (75 ml.)was stirred at laboratory temperature for 6 days. A solution ofpotassium carbonate (13.8 g.) in water (20ml.) was added, the mixturewas shaken, and the organic phase was separated, dried and evaporated todryness. The residue was stirred with petroleum ether and the mixturewas filtered. The filtrate was evaporated to dryness and the residualethyl N-(ethoxycarbonylmethyl)-p-trifluoromethylbenzimidate (12.0 g.)was dissolved in ethanol (50 ml.). Hydrazine hydrate (2 ml.) was addedand the mixture was heated under reflux for 2 hours, cooled andfiltered. The solid product was crystallised from methanol and there wasthus obtained3-p-trifluoromethylphenyl-4,5-dihydro-1,2,4-triazin-6(1H)-one, m.p.225°-226° C.

The process described above was repeated except that the appropriateethyl hippurate was used as starting material in place of ethylp-trifluoromethyl hippurate. There were thus obtained the compoundsdescribed in the following table:

    ______________________________________                                         ##STR15##                                                                                                            crystal-                                                                      lisation                              R.sup.7                                                                             R.sup.4     R.sup.5 R.sup.6                                                                             m.p. (°C.)                                                                     solvent                               ______________________________________                                        H     Cl          H       H     274-277 methanol                              H     CH.sub.3    H       H     259-266 methanol                              H     CH.sub.3 O  H       H     181-185 methanol                              H     C.sub.2 H.sub.5 O                                                                         H       H     204-205 methanol                              H     (CH.sub.3).sub.2 CHO                                                                      H       H     216     ethyl                                                                         acetate/                                                                      methanol                              H     CH.sub.3 CH.sub.2 CH.sub.2 O                                                              H       H     203-205 methanol                              H     H           Cl      H     218-221 methanol                              H     H           Br      H     234-237 ethanol                               H     H           CF.sub.3                                                                              H     196-199 methanol                              H     H           CH.sub.3 O                                                                            H     179-181 ethyl                                                                         acetate/                                                                      methanol                              H     H           CH.sub.3                                                                              H     197-201 methanol                              CH.sub.3 O                                                                          CH.sub.3 O  H       CH.sub.3 O                                                                          167-169 aceto-                                                                        nitrile                               CH.sub.3 O                                                                          CH.sub.3 O  CH.sub.3 O                                                                            H     199-202 aceto-                                                                        nitrile                               ______________________________________                                    

EXAMPLE 4

A stirred mixture of methyl N-(2-m-bromophenyl-2-oxoethyl)carbamate(9.67 g.), hydrazine hydrate (3.6 ml.), water (100 ml.) and isopropanol(50 ml.) was heated at 90°-100° C. for 3 days, cooled and filtered. Theproduct was crystallised from methanol and there was thus obtained6-m-bromophenyl-4,5-dihydro-1,2,4-triazin-3(2H)-one, m.p. 223°-225° C.

The methyl carbamate used as starting material was obtained as follows;

A solution of bromine (7.18 ml.) in methylene chloride (20 ml.) wasadded to a stirred solution of m-bromoacetophenone (25.6 g.) inmethylene chloride (80 ml.) and the mixture was stirred for 30 minutesand then evaporated to dryness under reduced pressure. The residue wascrystallised from methanol and there was thus obtained m-bromophenacylbromide.

A solution of m-bromophenacyl bromide (38.9 g.) in methylene chloride(50 ml.) was added to a stirred solution of hexamethylenetetramine (20.1g.) in methylene chloride (230 ml.) and the mixture was stirred atlaboratory temperature for 2 hours and then filtered. The solid residue(after washing with methylene chloride and drying) was added to astirred mixture of ethanol (100 ml.) and concentrated aqueoushydrochloric acid (45 ml.) and the mixture was stirred at laboratorytemperature for 17 hours and filtered. The solid product was washed withethanol, and there was thus obtained 2-m-bromophenyl-2-oxoethylaminehydrochloride.

A solution of methyl chloroformate (33.5 ml.) in ethyl acetate (20 ml.)was added to a stirred mixture of the above hydrochloride (42.75 g.)water (370 ml.), benzyltriethylammonium chloride (0.2 g.) and ethylacetate (350 ml.), and the mixture was stirred at 5° C. Sodiumbicarbonate (74 g.) was added portionwise and the mixture was stirred atlaboratory temperature for 15 hours. Ethyl acetate (200 ml.) was addedand the organic layer was separated. The aqueous layer was extractedtwice with ethyl acetate (75 ml. each time) and the combined organicsolutions were washed with water (50 ml.) and saturated aqueous sodiumchloride solution (50 ml.), dried over magnesium sulphate and evaporatedto dryness under reduced pressure. The residue was crystallised forethyl acetate and there was thus obtained methylN-(2-m-bromophenyl-2-oxoethyl)-carbamate, m.p. 101°-103° C.

The process described above was repeated using the appropriate methyl orethyl* N-(2-phenyl-2-oxoethyl)carbamate as starting material, and therewere thus obtained the compounds described in the following tables:

    __________________________________________________________________________     ##STR16##                                                                                                 Crystallisation                                  R.sup.7                                                                            R.sup.4                                                                             R.sup.5                                                                              R.sup.6                                                                            m.p. (°C.)                                                                   Solvent                                          __________________________________________________________________________    H    H     chloro H    229-230                                                                             methanol(1)                                      H    H     methoxy                                                                              H    207-209                                                                             methanol*                                        H    H     trifluoro-                                                                           H    196-197                                                                             toluene*(2)                                                 methyl                                                             H    H     H      methoxy                                                                            198-200                                                                             methanol*                                        H    methoxy                                                                             H      H    220-231                                                                             ethanol                                          H    methyl                                                                              methyl H    261-263(d)                                                                          ethanol                                          H    chloro                                                                              chloro H    248-251                                                                             ethyl acetate*(3)                                methoxy                                                                            methoxy                                                                             methoxy                                                                              H    195-196                                                                             aqueous methanol*                                H    CHCHCHCH     H    283-286                                                                             methanol/ethyl acetate                           __________________________________________________________________________

(1) The intermediate methyl N-(2-m-chlorophenyl-2-oxoethyl)carbamate hasm.p. 93°-95° C.

(2) The intermediate 2-m-trifluoromethylphenyl-2-oxoethylaminehydrochloride has m.p. 237°-239° C., and the intermediate ethylN-(2-m-trifluorophenyl-2-oxoethyl)-carbamate has m.p. 64°-66° C.

(3) The intermediate ethylN--[2-(3,4-dichlorophenyl)-2-oxoethyl]carbamate has m.p. 96°-100° C.

EXAMPLE 5

Ethyl bromoacetate (5.0 g.) was added to a stirred suspension of2,4-dimethoxythiobenzohydrazide (6.5 g.) in aqueous 3N-sodium hydroxidesolution (25 ml.) and the mixture was stirred at 25° C. for 18 hours andthen filtered. The solid product was purified by flash chromatography ona silica gel column (Merck 9385) using a 30:1 v/v mixture of chloroformand methanol as eluant. The aqueous filtrate was acidified with aqueous2N hydrochloric acid and the mixture was filtered. The solid products,both from the chromatographic purification and from the acidification,were combined and crystallised from aqueous methanol. There was thusobtained 2-(2,4-dimethoxyphenyl)-4H,6H-1,3,4-thiadiazin-5-one, m.p.162°-164° C.

The 2,4-dimethoxythiobenzohydrazide used as starting material wasobtained as follows:

A stirred mixture of 2,4-dimethoxybenzaldehyde (16.6 g.), morpholine (40g.) and sulphur (4.0 g.) was heated under reflux for 45 minutes and thenpoured into water (500 ml.). The oil which formed was separated andstirred with water, and the mixture was filtered. There was thusobtained as solid product 2,4-dimethoxythiobenzoylmorpholine, m.p.103°-105° C.

A mixture of the above compound (20 g.) and hydrazine hydrate (50 ml.)was stirred at 25° C. for 9 days, then at 65° C. for 24 hours andfinally at 25° C. for 3 days, filtered and the filtrate was evaporatedto dryness under reduced pressure. There was thus obtained as residue2,4-dimethoxythiobenzohydrazide which was used without furtherpurification.

The process described in the first paragraph above was repeated usingthe appropriate thiobenzohydrazide as starting material and there werethus obtained the compounds described in the following table:

    ______________________________________                                         ##STR17##                                                                                                           Crystal-                                                               m.p.   lisation                               R.sup.7                                                                              R.sup.4  R.sup.5  R.sup.6                                                                              (°C.)                                                                         Solvent                                ______________________________________                                        H      H        H        methoxy                                                                              140-142                                                                              methanol                               H      H        methoxy  H      128-129                                                                              aqueous                                                                       ethanol                                H      methoxy  H        H      162-165                                                                              aqueous                                                                       ethanol                                methoxy                                                                              H        H        methoxy                                                                              174    methanol                               H      H        methoxy  methoxy                                                                              169-170                                                                              methanol                               H      methoxy  methoxy  H      197-198                                                                              methanol/                                                                     methylene                                                                     chloride                               methoxy                                                                              H        methoxy  H      149-152                                                                              aqueous                                                                       methanol                               methoxy                                                                              methoxy  H        methoxy                                                                              125-126                                                                              acetonitrile                           methoxy                                                                              methoxy  methoxy  H      136-137                                                                              aqueous                                                                       methanol                               H      H        chloro   H      161-162                                                                              ethyl                                                                         acetate                                H      chloro   H        H      182-183                                                                              ethyl                                                                         acetate                                H      chloro   chloro   H      177-180                                                                              methanol                               ______________________________________                                    

The thio-benzohydrazides used as starting materials were prepared by asimilar process to that described in the second and third paragraphsabove, except that in two instances piperidine was used in place ofmorpholine. For those compounds wherein R⁶ is hydrogen, the lengthy (13day) process described in the third paragraph above was completed in 24hours. The intermediate thiobenzoylmorpholines andthiobenzoylpiperidines have the melting points shown in the followingtables:

    ______________________________________                                         ##STR18##                                                                    R.sup.7 R.sup.4   R.sup.5   R.sup.6 m.p. (°C.)                         ______________________________________                                                H         H         methoxy 94-95                                     H       H         methoxy   H       133-135                                   H       methoxy   H         H       106-108                                   methoxy H         H         methoxy 129-130                                   H       methoxy   methoxy   H       153-158                                   methoxy H         methoxy   H       84-85                                     methoxy methoxy   H         methoxy 140-143                                   methoxy methoxy   methoxy   H       138-142                                   H       chloro    H         H       139-141                                   ______________________________________                                    

    ______________________________________                                         ##STR19##                                                                    R.sup.4       R.sup.5 m.p. (°C.)                                       ______________________________________                                        H             chloro  59-61                                                   chloro        chloro  78-82                                                   ______________________________________                                    

EXAMPLE 6

Sodium hydride (0.1 g. of a 50% dispersion in mineral oil) was added toa stirred solution of 2-hydroxy-m-chloroacetophenoneethoxycarbonylhydrazone (3.6 g.) in ethanol (175 ml.) and the mixturewas stirred at 25° for 18 hours and then filtered. The solid product wascrystallised from ethyl acetate and there was thus obtained5-(m-chlorophenyl)-3H,6H-1,3,4-oxadiazin-2-one, m.p. 168°-170° C.

The 2-hydroxy-m-chloroacetophenone ethoxycarbonylhydrazone used asstarting material was obtained as follows:

Iodobenzene diacetate (32.2 g.) was added during 15 minutes to a stirredsolution of m-chloroacetophenone (15.4 g.) and potassium hydroxide (28.0g.) in methanol (300 ml.) which was kept at 0° C., and the mixture wasallowed to warm up to laboratory temperature, stirred at thattemperature for 2 hours and then evaporated to dryness under reducedpressure. The residue was shaken with water (200 ml.) and diethyl ether(200 ml.) and the ethereal solution was separated, dried over magnesiumsulphate and evaporated to dryness. A mixture of the residue, ethanol(35 ml.) and aqueous 2N-hydrochloric acid (35 ml.) was stirred at 25° C.for 20 hours and then filtered, and the solid product was crystallisedfrom methanol. There was thus obtained 2-hydroxy-m-chloroacetophenone,m.p. 103°-105° C.

A mixture of the above compound (5.5 g.), ethyl carbazate (3.3 g.) andethanol (150 ml.) was stirred at 25° C. for 60 hours and thenconcentrated to small volume by evaporation. The residue was heateduntil a clear solution was obtained, and was then cooled and filtered.There was thus obtained as solid residue 2-hydroxy-m-chloroacetophenoneethoxycarbonylhydrazone, m.p. 109°-110° C.

The process described above was repeated except that the appropriateacetophenone was used as initial starting material. There were thusobtained the compounds described in the following table:

    ______________________________________                                         ##STR20##                                                                                                        Crystal-                                                                      lisation                                  R.sup.7                                                                              R.sup.4   R.sup.5    m.p. (°C.)                                                                     solvent                                   ______________________________________                                        H      chloro    H          216-218 methanol                                  H      H         bromo      170-171 methanol                                  H      H         methoxy    184-186 ethanol/                                                                      cyclohexane                               H      methoxy   H          145-147 ethanol/                                                                      cyclohexane                               methoxy                                                                              methoxy   methoxy    218-220 ethanol                                   H      CHCHCHCH         199-202   methanol/                                                                     diethyl ether                               ______________________________________                                    

The intermediates which were characterised have the melting points shownin the following tables:

    ______________________________________                                         ##STR21##                                                                    R.sup.4       R.sup.5 m.p. (°C.)                                       ______________________________________                                        chloro        H       124-127                                                 H             bromo   105-107                                                 ______________________________________                                    

    ______________________________________                                         ##STR22##                                                                    R.sup.7  R.sup.4      R.sup.5  m.p. (°C.)                              ______________________________________                                        H        chloro       H        152-154                                        H        H            bromo    113-115                                        H        H            methoxy   97-100                                        methoxy  methoxy      methoxy  122-124                                        ______________________________________                                    

EXAMPLE 7

Sodium hydride (0.41 g. of a 50% dispersion in mineral oil) was added toa stirred solution of6-m-chlorophenyl-4,5-dihydro-1,2,4-triazin-3(2H)-one (Example 4; 21.1g.) in dimethylformamide (50 ml.) and after effervescence has ceasedmethyl iodide (0.59 ml.) was added. The mixture was stirred at 25° C.for 3 hours, allowed to stand for 20 hours and then evaporated todryness under reduced pressure. Tetrachloroethylene was added andremoved by evaporation three times, and the residue was purified bychromatography on a silica gel column using a 50:1 v/v mixture ofchloroform and methanol as eluant. The solid product was washed withdiethyl ether and there was thus obtained6-m-chlorophenyl-4,5-dihydro-4-methyl-1,2,4-triazin-3(2H)-one, m.p.116°-117° C.

What we claim is:
 1. A method for the treatment of hypertension, in awarm blooded animal in need of such treatment, which comprisesadministering to said animal an effective amount of a heterocycliccompound of the formula: ##STR23## wherein X is --CR¹ R² and Y is --O--,wherein R¹ and R², which may be the same or different, each is hydrogenor alkyl of up to 4 carbon atoms;wherein either R⁴ is hydrogen, fluoroor chloro, or alkyl, alkenyl, halogenoalkyl, aminoalkyl, hydroxyalkyl,alkoxyalkyl or alkoxy each of up to 6 carbon atoms, and R⁵, R⁶ and R⁷,which may be the same or different, each is hydrogen, fluoro, chloro,bromo or iodo, or alkyl, alkenyl, halogenoalkyl, aminoalkyl,hydroxyalkyl, alkoxyalkyl or alkoxy each of up to 6 carbon atoms,provided that R⁴, R⁵, R⁶ and R⁷ are not all hydrogen; or R⁴ is bromo andR⁵, R⁶ and R⁷ have the meanings stated above, provided that R⁵, R⁶ andR⁷ are not all hydrogen; or R⁴ and R⁵ together, or R⁵ and R⁶ together,or R⁴ and R⁷ together, form the --CH--CH═CH═CH-- group and the other twoof R⁴ , R⁵ , R⁶ and R⁷ have the meanings stated above.
 2. A method ofthe treatment of acute or chronic heart failure in a warm blooded animalin need of such treatment, which comprises administering to said animalan effective amount of heterocyclic compound of the formula: ##STR24##wherein X is --CR¹ R² and Y is --O--, wherein R¹ and R² , which may bethe same or different, each is hydrogen or alkyl of up to 4 carbonatoms;wherein either R⁴ is hydrogen, fluoro or chloro, or alkyl,alkenyl, halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl or alkoxyeach of up to 6 carbon atoms, and R⁵ , R⁶ and R⁷ , which may be the sameor different , each is hydrogen, fluoro, chloro, bromo or iodo, oralkyl, alkenyl, halogenoalkyl, aminoalkyl, hydroxyalkyl, alkoxyalkyl oralkoxy each of up to 6 carbon atoms, provided that R⁴ , R⁵ , R⁶ and R⁷are not all hydrogen; or R⁴ is bromo and R⁵, R⁶ and R⁷ have the meaningsstated above, provided that R⁵, R⁶ and R⁷ are not all hydrogen; or R⁴and R⁵ together, or R⁵ and R⁶ together, or R⁴ and R⁷ together, form the--CH═CH--CH═CH-- group and the other two of R⁴ , R⁵ , R⁶ and R⁷ have themeanings stated above.